Inferior Olivary Nuclear Complex Research Articles

Immunohistochemical characterization of axon terminals of the adult rat cerebellar cortex

Aim of the present study was to immunohystochemically characterize the glutamatergic terminals in the cerebellar cortex. The study was carried out on adult rat, using immunohistochemistry for the vesicular transporters of glutamate, VGLUT1 e VGLUT2, and synaptophysin. Results. Terminals positive for VGLUT1 e VGLUT2 were observed in the molecular layer (ML) and granular layer (GL). ML. VGLUT1-positive terminals appeared very numerous, homogeneously distributed throughout the layer with a distribution pattern resembling that of the parallel fiber terminals. VGLUT2-positive terminals appeared displaced along distinct spiral lines extending from the deeper part of the layer up to the its superficial part, likely corresponding to synapses between climbing fibers and Purkinje neuron dendrites. No colocalization of VGLUT1 and VGLUT2 was observed in ML. Double labelling for VGLUT1 and synaptophysin and, respectively, VGLUT2 and synaptophysin revealed colocalization, suggesting the axon terminal nature of the immunolabelled elements. Interestingly, some elements appeared synaptophysin positive, but negative for VGLUT1 and VGLUT2. In GL, VGLUT1 and VGLUT2 positive terminals displayed similar distribution patterns, They appeared clustered in restricted regions of the layer, scattered within granule neurons, at the level of synaptic glomeruli. Most of these terminals showed a colocalization of VGLUT1 and VGLUT2. However a part of them shows positivity for VGLUT2 and negativity for VGLUT1. All the VGLUT1 and VGLUT2 positive elements also displayed positivity for synaptophysin. Finally, like in ML, some elements appeared synaptophysin positive, but negative for VGLUT1 and VGLUT2. Conclusion. The results indicate that the glutamatergic terminals in the cerebellar cortex may be differentiated combining Immunohistochemistry for VGLUT1 and VGLUT2. Moreover, the results identify subpopulations within terminals of the parallel, climbing and mossy fibers. In particular, a subpopulation of mossy fiber terminals, displaying positivity for VGLUT2 and negativity for VGLUT1, are different from the vast majority of mossy fiber terminals, which display for both VGLUT1 and VGLUT2, but similar to climbing fiber terminals. It is intriguing to hypothesize that these mossy fibers may constitute a contingent of mossy fiber originated in the inferior olivary nuclear complex.

Immunohistochemical mapping of adrenomedullin in the human medulla oblongata

We studied by immunocytochemistry the expression of adrenomedullin (AM) in the human medulla oblongata, sampled from 13 adult subjects (mean age: 38 years), whose medical history was negative for neurological and neurovascular pathologies. Immunoreactive neurons were found in the medulla oblongata with statistically significant differences among the various nuclei (one-way ANOVA, P < 0.001). The hypoglossal nucleus showed higher AM expression than that of the spinal tract of the trigeminal nerve ( P < 0.05), solitary tract nucleus ( P < 0.05), nucleus intercalatus ( P < 0.05), and area postrema ( P < 0.05). The arcuate nucleus and inferior olivary nuclear complex showed lower AM expression than the hypoglossal nucleus ( P < 0.001), vestibular nuclei ( P < 0.01), cuneate and gracile nuclei ( P < 0.05), lateral column of the reticular formation ( P < 0.05), and nucleus ambiguous ( P < 0.05). Furthermore the nuclei were grouped with reference to their function, into somatic sensitive nuclei, somatic motor nuclei, visceral nuclei, reticular formation, and nuclei involved in cerebellar functions. The ANOVA revealed statistically significant differences ( P < 0.001) in mean AM scores among the different groups. Nuclei involved in cerebellar function showed the lowest mean AM score ( P < 0.05). The difference in AM score between somatic motor nuclei and visceral nuclei was also statistically significant ( P < 0.05). Widespread AM immunoreactivity in the nuclei of the medulla oblongata may account for the role of the peptide in neuronal function and regulation of regional blood flow. Differences in the expression of AM in the nuclei studied indicate the different involvement of AM in neurotransmission and neuromodulation.

Involvement of precerebellar nuclei in multiple system atrophy.

In this semiquantitative study based on 26 post-mortem cases, we describe the involvement of precerebellar nuclei in multiple system atrophy (MSA), a progressive degenerative disorder of the human central nervous system characterized by abnormal, argyrophilic and alpha-synuclein immunopositive intracellular inclusions within selectively vulnerable oligodendrocytes and nerve cells. The Campbell-Switzer silver-pyridine technique with alpha-synuclein immunoreactions using 100-microm thick sections is recommended over more conventional methods, thereby permitting visualization of the pertinent lesions in greater detail and facilitating post-mortem diagnosis of MSA specimens. Affected oligodendrocytes occur in specific fibre tracts and grey matters, with most pathology being observed in projections from the precerebellar nuclei to the cerebellum (ponto-cerebellar, olivo-cerebellar, reticulo-cerebellar tracts) and in descending/ascending fibre tracts of the motor system (cortico-pontine, cortico-bulbar, cortico-spinal, spino-reticular, spino-olivary, spino-cerebellar tracts). Three types of abnormal intraneuronal aggregations occur: (i) a loosely woven network within the cell nucleus; (ii) a latticework accumulating in peripheral portions of the cell body; and (iii) irregularly outlined patches of compact, intensely argyrophilic material usually located within deposits of lipofuscin granules. Counter-staining for the presence of extraneuronal lipofuscin can aid neuropathologists in the recognition of lost existent neurones in MSA. Neurones with inclusion bodies occur in the inferior olivary nuclear complex, lateral reticular nucleus, external cuneate nucleus, conterminal nucleus, interfascicular nucleus, nucleus of Roller, dorsal paramedian reticular nucleus, subventricular nucleus, arcuate nucleus, pontobulbar body and pontine grey. The lateral reticular nucleus and accessory nuclei of the inferior olive sustain the most damage and reveal prominent neuronal loss, followed by the pontobulbar body and arcuate nucleus. The uniformly bilateral damage and, in some cases, even obliteration of the nuclei studied, supply additional evidence for the pathoanatomical substrata of the cerebellar dysfunction that reportedly emerges in the clinical course of MSA.

Lesioning of the inferior olive using a ventral surgical approach. Characterization of temporal and spatial astrocytic responses at the lesion site and in cerebellum.

Activated astrocytes, intrinsic components of both local and remote (axonal target regions) central nervous system injury responses, are now recognized as active metabolic and regulatory mediators in many neurological disorders. To further define these responses, we devised a new ventral surgical approach to unilaterally lesion the inferior olivary nuclear complex, which has a single predominant remote target, the cerebellum. Activated astrocyte number, volume, and density, as well as the total volume of brainstem involved in the astrocytic response, all peaked at postlesion day (pld) 4, returning toward, but not to, unoperated control values at pld 24 (p < 0.05). In contrast, the peak astrocyte response in the cerebellum was delayed, being greatest at pld 6 (p < 0.05 compared to control or pld 2). These responses were associated with increases in overexpression of S100 beta, an astrocyte-derived neurite growth factor, and with an increase in cerebellar steady-state levels of a neuronal injury response protein, the beta-amyloid precursor protein (beta-APP). This is similar to correlated increases in these two proteins that are found in epilepsy and Alzheimer disease. Our studies defining remote astrocytic and neuronal responses may be important for understanding glial-neuronal mechanisms underlying the spread of neuropathological changes in conditions such as Alzheimer disease.

The postnatal development of the pont- and olivocerebellar neurons in the rat

To study the postnatal development of the cerebellar afferent neurons in the inferior olivary nuclear complex as the climbing fiber and in the pontine nuclei as the mossy fiber, HRP (Sigma type VI) has been injected into cerebellar vermis and hemispheres of 1, 3, 5, 7, 14, 21 and 28 day after birth, and observed the HRP-labeled neurons in the inferior olivary nuclear complex and pontine nuclei with the light microscope.In the inferior olivary nuclear complex of the hemispheric injection the HRP-labeled neurons were mainly distributed throughout the principal nucleus and the rostral part of the medial accessory nucleus contralatelly, and in that of the injection into vermis the HRP-labeled neurons in the caudal part of the medial accessory nucleus bilaterally. Also, in the pontine nuclei of the hemispheric injection the HRP-labeled neurons were distributed thoughout almost the pontine nuclei contralaterally and partially the dorsal part of pontine nuclei ipsilaterally, and in them of the injection into vermis the HRP-labeled neurons the dorsal part of pontine nuclei bilaterally. These distributions in both nuclei are almost remained from 1 to 28 day after birth.Subsequently, we have studied the structure of the HRP-labeled neurons in the both nuclei at 1, 7 and 28 day after birth. In the pontine nuclei, at 1 day the HRP-labeled neurons were immature and the structure of their dendrites showed the profile of cytoplasmic processes, but at 7 and 28 day their differentiations were more advanced. While in the inferior nuclear complex, HRP-labeled neurons were already mature at 1 day after birth.From these findings it is concluded that the projection fibers derived from the inferior olivary nuclear complex and the pontine nuclei have already invaded into the cerebellum and the distribution of their cerebellar afferent neurons in both nuclei seems to be determined at 1 day after birth although the neurons are immature.

Inferior olivary nuclear complex of the rat: Morphology and comments on the principles of organization within the olivocerebellar system

This study was undertaken (1) to provide a description of the normal morphology and anatomical interrelationships within the inferior olivary cell groups and (2) to determine the topographical organization of projections from this nuclear complex to the cerebellum. Conventional histological methods and the technique of retrograde transport of horseradish peroxidase (HRP) and WGA-HRP in conjunction with the sensitive chromogen tetramethyl benzidine were used in this series of experiments. In common with that of other animals, the inferior olivary nucleus of the rat consists of three subdivisions: the medial accessory olive (MAO), dorsal accessory olive (DAO), and principal olive (PO). The MAO is made of several subnuclei including a, b, c, and nucleus beta. On the basis of their common connections, the smaller subnuclei, dorsal cap, ventrolateral outgrowth, and dorsomedial cell column can be considered as parts of the MAO. The DAO is made of two subdivisions or lamellae--the dorsal and ventral folds--joined together laterally to form a twisted V-shaped structure. The principal olive consists of dorsal and ventral lamellae. A point-to-point projection was determined for four areas of the cerebellum: the anterior lobe, the posterior vermis, the intermediate and the lateral cerebellum. Analysis of the details of the projection system revealed that distinct groups of cells, here referred to as lamellae, project to sagittal zones of the cerebellum. (1) The medial accessory olive appears to be composed of three lamellae: horizontal, vertical, and rostral. The horizontal lamella (elsewhere denoted as groups a and b) projects to a sagittal zone in the vermal anterior lobe. The vertical lamella (groups c, beta, dorsal cap, ventrolateral outgrowth, and dorsomedial cell column) projects to a sagittal zone in the posterior vermis and the flocculus, and the rostral lamella projects to the lateral cerebellum. (2) The dorsal accessory olive is composed of two distinct lamellae which we have previously denoted as the dorsal and ventral folds. The dorsal fold projects to the vermal anterior lobe and receives afferents from the spinal cord, whereas the ventral fold projects to a sagittal zone in the intermediate cerebellum and receives afferents primarily from dorsal column nuclei. (3) The principal olive contains the two familiar lamellae: dorsal and ventral lamellae, each of which projects to a specific sagittal strip in the lateral cerebellum.(ABSTRACT TRUNCATED AT 400 WORDS)

Autoradiographic localization of calcitonin gene-related peptide binding sites in human and rat brains

125I-calcitonin gene-related peptide (CGRP) binding sites were mapped in the human brain and rat brains by in vitro macroautoradiography, and compared to each other. Binding experiments were made to characterize 125I-CGRP binding on the human and rat brains. Scatchard analysis of saturation experiments from slide-mounted sections of the human and rat cerebellum displayed 125I-CGRP binding sites with a dissociation constant ( K d ) of 0.17 nM and 0.11 nM, respectively, and a maximal number of binding sites (B max) of 96.8 fmol/mg and 23.0 fmol/mg protein. 125I-CGRP binding was time-dependent, reversible and saturable with high affinity in the brains. Autoradiograms showed a discrete distribution of 125I-CGRP binding sites throughout the brains of human and rat with patterns similar to each other. In the human brain, the highest binding was seen in the cerebellum, inferior olivary nuclear complex, certain parts of the central gray matter, arcuate nuclei of the medulla oblongata and dorsal motor nucleus of the vagus, and densities of CGRP-binding sites were high in the nucleus accumbens, amygdala, tail of the nucleus caudatus, substantia nigra, ventral tegmental area, medial portion of the inferior colliculus, medial pontine nuclei, locus coeruleus, inferior vestibular nucleus, substantia gelatinosa of the spinal trigeminal nucleus, nucleus of the solitary tract and nucleus cuneatus lateralis. In the rat, high densities were found in the hippocampus pars anterior, nucleus accumbens, ventral and caudal portions of the nucleus caudatus-putamen, central and basolateral nuclei of the amygdala, caudal portion of the insular cortex, medial geniculate body, superior and inferior colliculi, certain portions of the central gray matter, locus coeruleus, inferior olivary nuclei, vagal complex, nucleus cuneatus lateralis and cerebellum. In contrast, in both species, most of the cortical areas including the hippocampus, most of the thalamus, and hypothalamus exhibited few binding sites. In addition, high quantities of the binding sites were seen on the pia mater and on walls of blood vessels in the brain and subarachnoidea. These results revealed essentially homologous locations of CGRP binding sites in the human and rat central nervous systems and well corresponding distributions of binding sites and endogenous CGRP-like immunoreactivity.

A Golgi study of the development of the inferior olivary nuclear complex in the chicken.

The present study is an examination of the qualitative and quantitative changes in the morphology of neurons in the inferior olivary nuclear complex ( IOC ) of the chicken. The development of the chicken IOC was studied with the Golgi technique between embryonic day 11 (E11) and posthatch day 35 ( P35 ). The olivary cells change most between E11 and E19 and are essentially mature (i.e., similar to P35 ) at E19 . These changes chiefly involve a gradual loss of features that typify immature growing cells (e.g., growth cones, growth buds, filopodia, beaded dendrites); from E11 to P35 there is an increase in the soma size by 42%, an increase in the dendritic field size by 49%, and a decrease in the number of dendritic branches by 47%. A minor but significant fall in the number of dendrites per neuron between E11 and E19 was observed, but as there is no significant difference between E11 and P35 , the relevance of this observed change, if any, is unclear. On the basis of dendritic branching, it appears that one type of olivary neuron is present in the chicken, which is similar to the type of neuron found in the caudal medial olive (MO) and the caudal dorsal olive (DO) of mammals ( Schiebel and Schiebel , '55; Rutherford and Gwyn , '80). This finding correlates with the proposal that the avian IOC corresponds mostly to the mammalian MO and DO and that only a small portion corresponds to the mammalian principal olive ( Furber , '83).

Ratio of inferior olivary cells to Purkinje cells in a marsupial (&lt;i&gt;Trichosurus vulpecula&lt;/i&gt;)

An indirect estimate of the extent of branching of the olivary axons in the cerebellum in a marsupial (Trichosurus vulpecula) was carried out. The cells in the inferior olivary nuclear complex (IOC) of both sides were estimated (mean = 57,200), as were the cerebellar Purkinje cells (mean = 881,300). Assuming that all climbing fibers arise from IOC cells and that each Purkinje cell receives a climbing fiber input, each IOC cell sends climbing fiber terminals to 15 Purkinje cells.

Origin of cerebellar climbing fibers in the rhesus monkey.

AbstractThe inferior olivary nuclear complex is generally considered to be the major source of climbing fibers to the cerebellum (Bell and Dow, '67). To test the validity of this statement, experiments using monkeys were designed in which the olivocerebellar fibers were transected in their course through the medulla to the contralateral hemicerebellum. After allowing for anterograde degeneration of these transected fibers, the cerebellum of each monkey was stained and examined for the presence and condition of climbing fibers. In each monkey olivocerebellar fibers were transected at one of three sites: (1) within the right inferior olivary nucleus in one rhesus monkey, (2) at the decussation of the olivocerebellar fibers, within the region of the raphe, in five monkeys and (3) in the left parasagittal plane, just lateral to the inferior olivary nucleus, in one monkey. No noticeable reduction was found in the number of silver stained climbing fibers associated with the Purkinje cells of each hemicerebellum after these lesions. None of the monkeys exhibited durable, specific cerebellar signs. On the basis of the histological evidence obtained from the above experiments, it is concluded that the inferior olivary complex is not the major source of climbing fibers to the cerebellum.Climbing fibers were readily identified in each of the sections examined. However, silver‐stained climbing fibers were not associated with many Purkinje cells in every one of these sections. There were 1.7 times more Purkinje cells without climbing fibers than those with climbing fibers. This ratio of 1.7 to 1 characterized normal cerebella as well as both hemispheres of the cerebella of the cerebella of the experimental monkeys.

Cell frequencies in the human inferior olivary nuclear complex.

AbstractCerebellar afferents from the inferior olivary nuclei arise from about one million nerve cells. This figure was determined by counts and estimates carried out on four complete series of human brain‐stem sections of a new‐born, a three‐month‐old infant, a 42‐year‐old male and a 56‐year‐old male. Cell frequencies in all four cases were nearly identical. About 7% of this total belongs to the two accessory nuclei, believed to project to the archeocerebellar cortex.Cell sizes differ between the main and the two accessory olivary nuclei, the former having a mean cell size of about 400 μ2, the latter about half this size. Comparing infant and adult cell size, there is a threefold increase in volume from infancy to adulthood. Packing density of nerve cells in the infants is about twice that of the adults. The ratio of nerve cells to glia cells is 1:4 in the adults and 1:6.7 in the infants.